Heat exchangers are commonly found in many systems where it is necessary for the heat energy of one fluid to be exchanged with the heat energy of another fluid for a variety of different technical reasons. The exchange of heat may be related to the utilizing of a maximum amount of available energy within the system or may in other cases be related to heating or cooling a medium that is then used to regulate a temperature of an object or an environment.
Heat exchangers typically include a plurality of heat exchanger tubes that extend between an inlet header and an outlet header. The heat exchanger tubes carry a first fluid therein while a second fluid is passed over or between the heat exchanger tubes. In some instances, a plurality of fins or other surface area increasing features may extend from one heat exchanger tube to an adjacent heat exchanger tube. The heat energy must be exchanged between the two fluids via walls of the heat exchanger tubes, hence an efficiency of the heat exchanger is largely dependent on the ability of either of the first fluid and the second fluid to transfer heat energy through walls of the tubes.
One method of increasing the heat transfer between a fluid and the wall of the tube is to increase the turbulence of the fluid at a boundary between the fluid and the wall of the tube in order to reduce the thermal boundary layer thickness. However, highly efficient heat exchangers that promote turbulence in one of the fluids flowing through the heat exchanger often require exceedingly complex modifications to the interior of the heat exchanger tube. For example, the heat exchanger tube may be modified by the addition of an internal insert that increases the turbulence of the fluid flowing therein or the heat exchanger tube may require a complex manufacturing process to introduce additional internal features for increasing the turbulence of the fluid. In either case, the cost and complexity of producing such turbulence inducing features within the heat exchanger tube may be cost prohibitive.
One form of heat exchanger that may require an increase of turbulence within the heat exchanger tube is the Transmission Oil Cooler (TOC). A common and cost effective method of forming a TOC includes extruding aluminum to form elongated multi-port tubing. However, creating additional physical features to increase the turbulence in the laminar flow of the oil used in the TOC is difficult and expensive within the multi-port extruded tube due to the use of complex and expensive manufacturing processes.
It would therefore be desirable to produce heat exchanger tubes manufactured using a low cost extrusion process while maintaining a high heat transfer efficiency through the introduction of turbulence within the extruded heat exchanger tubes.